It is known to use a lightning protection arrangement to protect wind turbine rotor blades against damage by a lightning strike. For this purpose, a lightning receptor is generally arranged in the region of the blade tip. The current of lightning striking into the lightning receptor is then diverted, via a lightning conductor, toward the blade root, and from there, via the nacelle and the tower of the wind turbine, into the ground. If a plurality of electrically conductive elements are arranged, more or less in parallel, in the wind turbine rotor blade, electromagnetic induction in the case of a lightning strike causes large potential differences between the electrically conductive elements and the potential differences can lead to flashovers or even to the destruction of the wind turbine rotor blade. It is known to counteract flashovers of this kind using potential equalization elements.
Potential equalization of this kind is necessary, in particular, if one of the electrically conductive elements is an electric heating device for de-icing the surface of the wind turbine rotor blade. These heating devices are provided with a power supply and have to be electrically isolated from the lightning protection system during operation. For this purpose, spark gaps may be provided in the interior of the rotor blade, between the heating device and the lightning protection arrangement, as shown in U.S. Pat. No. 6,612,810. In the event of a lightning strike, these spark gaps are bridged and establish potential equalization between the heating device and the lightning protection arrangement.
United States patent application publication 2015/0204311 shows a wind turbine rotor blade having an electrical heating device and a lightning conductor. The heating device and the lightning conductor are connected to one another at several points over the length of the rotor blade, via spark gaps. The spark gaps are arranged in the interior of the rotor blade, in combination with the lightning receptors.
In order to ensure the operational reliability of the lightning protection arrangement, the functional performance of the spark gaps must be checked regularly. In this case, in particular, spark gaps which are arranged in the blade tip region are accessible only with a great deal of difficulty.